Hoffman, 46, was found dead Sunday of an apparent heroin overdose in his apartment. He leaves behind his partner of 15 years, Mimi O'Donnell, and their three children.

The ceremony was being held at the Church of St. Ignatius Loyola, the same limestone church that hosted the funerals of Jacqueline Kennedy Onassis, Lena Horne and Aaliyah. The 1898 Baroque-style marble interior is reminiscent of a Roman basilica.

A larger memorial service is being planned for later this month. On Thursday evening, family and close friends gathered for a private wake at the Frank E. Campbell Funeral Home in Manhattan.

The rumpled, heavy-set Hoffman was known to dive into roles and was nominated for Academy Awards four times: for "Capote," ''The Master," ''Doubt," and "Charlie Wilson's War." He also received three Tony nominations for his work on Broadway, which included an acclaimed turn in 2012 as the weary and defeated Willy Loman in "Death of a Salesman."

The theater community mourned the actor Wednesday with a candlelit vigil outside his beloved LAByrinth Theatre Company downtown and with Broadway's marquee lights turned off for a minute.

More tests are needed to determine what exactly killed Hoffman, who was found with a syringe in his arm and what authorities said were dozens of packets of heroin in his apartment. Autopsy results were inconclusive, authorities said this week.

Hoffman spoke candidly over the years about past struggles with drug addiction. After 23 years sober, the versatile actor reportedly checked himself into rehab for 10 days last year after relapsing in 2012.

Amid an investigation into Hoffman's death, three people have been arraigned on drug charges, including one who is facing a felony charge of heroin possession with intent to sell. Lawyers for the three people charged vigorously denied their clients had any role in Hoffman's death.

Most of those who attended the funeral had deep ties to Hoffman. He and Blanchett co-starred in "The Talented Mr. Ripley," and Hoffman starred in Lee's "The 25th Hour." Burstyn and Hoffman were in "Red Dragon," and Hawke co-starred with Hoffman in "Before the Devil Knows You're Dead." Slattery directed Hoffman in his new film "God's Pocket," and Nichols directed Hoffman on Broadway in "Death of a Salesman." Phoenix shared the screen with Hoffman in "The Master."